How Windows 8 scaling fails on high-PPI displays

In our original review of Asus' Zenbook Prime, we lamented that the notebook's high-density display—a beautiful 13.3" IPS specimen with a 1920x1080 resolution—wasn't terribly well supported in Windows 7. The operating system happily applied the correct PPI setting and enlarged text and widgets alike, but certain apps scaled poorly, and web browsing in particular involved ugly compromises.

At the same time, we expressed tentative optimism about Windows 8, whose improved support for high-density screens Microsoft proudly announced earlier this year. We figured the new OS would better harness the Zenbook Prime's magnificent panel, especially in the newfangled Metro user interface.

Now, we're about to see if that optimism was warranted.

We've grabbed the RTM release of Windows 8 from the MSDN Evaluation Center and loaded it onto the Zenbook Prime. This is the exact same build of Windows 8 that's going to show up in stores and on pre-built PCs next month, so our experience should be representative of what you'll see then. Has Microsoft made substantial improvements to high-PPI display support as we hoped, or did the company drop the ball? Let find out.

The problem with Windows 7
Before we get started, let's clarify exactly what Windows 7 does wrong with high-density panels. By default, the operating system applies a 125% scaling setting on the Zenbook Prime. That setting enlarges user-interface widgets and text throughout the OS, which makes your typical Windows desktop (just to show one example) appear like so:

Click for full-size.

The interface is roughly the correct size for the 13.3" panel. More pixels are used to draw each character, each button, and each icon. The result looks and works rather well.

Sadly, problems persist in third-party applications. Older software often doesn't support the scaling well, and skinned apps like Valve's Steam client are hit-and-miss. Windows 7 isn't really to blame, though. These issues are more about software vendors failing to adopt newer APIs—or not making their custom widgets and skins scalable. As high-PPI displays become more and more common, those vendors will hopefully fall in line.

Click for full-size.

Third-party apps weren't really our main concern when using the Zenbook Prime. We were more worried about web browsing. For pages to be readable on the 13.3" 1080p display, they must be scaled up—and browser-based scaling is fraught with problems. Allow me to reiterate my explanation from the Zenbook Prime review:

You've got three choices. You can stick to the 100% setting, where text is much too tiny for comfortable reading. (See above. The fonts in Windows Explorer are the right size for the display; the ones on TR aren't.) You can scale text independently of graphics, which often breaks page layouts. The third option is to tell the browser to scale up the page by 25%, and that wreaks havoc with images.

Oh, photos might look okay. You might not even notice the difference in text-heavy websites like Reddit or Craigslist, since fonts scale without putting up a fight. Go to any graphically heavy page, though, and you'll see blurry pixels and scaling artifacts if you look close. Some browsers scale graphics better than others, but no matter what you do, the web is always going to look either too small or too ugly.

Apple's Retina MacBook Pro deals with this problem with a little more elegance. The system's 2880x1800 resolution has four times the pixel count of 1440x900, its reference resolution for UI scaling. In most of the operating system—and in Retina-ready apps—objects are drawn with exactly four times the number of pixels. When Retina-ready graphics aren't available, like on the web, each source pixel is simply mapped to four pixels on the display. You get jaggies, naturally, but at least scaling is consistent, proportional, and free of weird artifacts.

For reference, here are examples of the artifacts Internet Explorer 9 introduces in the default scaling mode. That mode offers the least awful combination of layout consistency and readability, yet it still has obvious shortcomings:

Note the grey line above the podcast and system guide logos. IE9 also mangles the fading one-pixel lines next to the feature articles header. Artifacts like those are all too common on scaled pages. Of course, all images must be scaled, so even photos end up looking a little fuzzy. Slight fuzziness may be easy enough to get used to, but visual corruption is not.

For what it's worth, Chrome handles itself a bit better in Windows 7 on the Zenbook Prime. When we pull up TR, Google's browser only appears to stumble with the navigation bar. The white rounded rectangles that surround selected menu items have jagged edges, and an uneven line appears between the "More..." link and the menu that pops under it.

Windows 8 may not address Chrome's scaling woes, but it's hopefully going to take care of Internet Explorer. Or is it? Cue dramatic music.